This invention relates generally to a media feeding apparatus for image forming devices. More specifically, the present invention relates to a closed-loop feedback control system for a media feed apparatus.
Image forming devices, e.g., printers, copiers, facsimile machines, and the like typically include a media tray configured to store at least one sheet of media (e.g., paper, textiles, mylar, and the like) to be fed into the image forming device during an image forming operation. Some image forming devices employ a feed arm assembly to actuate the feeding of a sheet of media from the media tray. The feed arm assembly may include a feed arm pivotally attached at a position generally above the media tray and a pick roller configured to contact and advance a sheet of media by operation of its rotation. At least by virtue of the pivoted attachment of the feed arm, as the level of media in the media tray decreases, the feed arm typically rotates to thereby substantially maintain contact between the pick roller and a top sheet of media in the media tray.
Conventional image forming devices may also include a sensor located generally upstream of a pair of pinch rollers. The sensor is typically configured to be tripped as a sheet of media is fed from the media tray and into the pinch rollers. When the sensor is tripped or some time shortly thereafter, the pick roller is oftentimes deactivated such that the sheet of media may be advanced into the image forming device by operation of the rotation of the pinch rollers. The sensor is also typically provided to determine whether an error in the media advancement has occurred, e.g., a paper jam. In one respect, a predetermined time interval may be set for a sheet of media to be advanced from the media tray to the sensor. An error signal may be displayed when a sheet of media has not advanced to the sensor within the predetermined time interval. However, as the sheets of media are advanced into the image forming device, the level of the media within the media tray decreases, thus increasing the amount of time necessary for a sheet of media to trigger the sensor. The range in the amount of time necessary for sheets of media to trigger the sensor based upon the height of the media in the media tray generally increases the complexity of detecting the occurrences of media advancement errors.
In one respect, some media tray devices attempt to overcome the above-described problem by employing a spring-loaded device to maintain the sheets of media in the media tray at a substantially constant height. One drawback of these types of media tray devices is that they are relatively complex compared to non-lifting type media trays. Another drawback is that they typically must be removed from an image forming device in order for the supply of media to be replenished in the media tray.
According to one aspect, the present invention pertains to a device having a feed arm assembly and an idler roller. The feed arm assembly includes a first end and a second end. The first end is pivotally connected to a substrate at a pivot point. The second end includes a pick roller configured to cause a sheet of media to advance along a feed path. In addition, an idler roller containing a sensor is connected to the feed arm assembly. The sensor is configured to monitor the advancement of the sheet of media.
According to another aspect, the present invention relates to a method for feeding media sheets. In the method, a pick roller of a feed arm assembly is activated to thereby cause a sheet of media to travel along a feed path. By virtue of the travel of the sheet of media and the substantial contact between an idler roller and the sheet of media, the idler roller containing a sensor is caused to rotate. The rotation of the idler roller may be sensed to determine the speed of media advance. In addition, a closed-loop feedback of media advance along the feed path may be formed by sensing the rotation of the idler roller.
In one respect, the closed-loop feedback of media advance is implemented to alter the time to return an error signal.
In another respect, the closed-loop feedback of media advance is implemented to alter the speed at which the sheets of media advance along the feed path.
In yet another respect, the closed-loop feedback of media advance is implemented to calculate the level of media in a media tray.
According to yet another aspect, the present invention pertains to a computer readable storage medium on which is embedded one or more computer programs, where the one or more computer programs implement a method for feeding media sheets. The one or more computer programs include a set of instructions for activating a pick roller of a feed arm assembly to thereby cause a sheet of media to travel along a feed path, where the manipulation of the sheet of media is operable to cause an idler roller containing a sensor to rotate. The one or more computer programs further include a set of instructions for determining the speed of the media advance. In addition, the one or more computer programs further include a set of instructions for forming a closed-loop feedback of media advance along the feed path.